Footwear soles with massaging effects are known and widely used, however they have several drawbacks. In prior art soles, the foot massage carried out with the stress discharged by the foot on the ground when walking is partially retransferred to the foot at preferred areas by using inserts mounted in the sole. Prior art inserts are often composed of materials with different elasticity with respect to the sole material and are inserted in the sole. A solution according to prior art, for example, provides areas with different elasticity inside the sole by putting inserts that are embedded in the sole material, that is, in the footwear sole at least an insert is incorporated having elasticity and density different with respect to the remaining part of the sole, and so when walking, areas made of different materials and composing the footwear sole react in a different way, that is they retransfer to the foot the stressing exerted in differentiated manner among areas with different elasticity, or density, substantially producing a kind of massage to the foot.
Alternatively, according to prior art, elastic or spring inserts have been provided still inside the sole.
However, these solutions have some drawbacks mainly due to the fact that the foot massage areas are not confined in the selected areas, but often a very large foot area is concerned, causing to be massaged even areas that were not intended to be massaged.
In order to obtain a massage of the foot in prior art solutions, massage inserts are positioned between the sole and the insole, or as an alternative, only on the sole. Thus there is provided a message that however, due to the presence of the insole, is substantially distributed on all the user foot sole. Usually there is provided an insole between the massage insert and the foot in order to increase comfort, since prior art massage inserts are made from materials that do not adapt to the foot shape and, according to prior art, the insert is positioned under the insole, particularly on the sole, in order to allow the user's foot to rest on the soft insole, that in turn rests upon the massage insert. Thus in prior art soles a massage of the foot can be obtained without reducing comfort, however causing the massage to be distributed on large areas of the foot sole, making the massage less specific and less directed than desired. In an alternative according to prior art, it is possible to localize the massage area, but this involves reducing comfort for the user by removing the insole.
A further drawback of the prior art is that inserts with different elasticity are often inserted inside the sole, that is embedded in the sole material, which involves high manufacturing costs. For example, in a mass production of a considerable number of soles, the inserts have to be inserted directly inside the sole material, involving considerable difficulties and high manufacturing cost and time.
Generally, in prior art different types of inserts have been produced for foot massage, such as for example springs or point-like inserts coming out from the sole towards the foot or the like. However, a main problem is that said inserts provide a massage to areas that are not confined, and thus even to areas where the massage is not desired, with the further drawback that the massage in the areas of interest is reduced.
Moreover, in prior art soles, inserts are often homogeneously composed of the same material that has the same elasticity. This causes the foot to be often in contact with a material that has very good elasticity, but with a poor comfort for the foot, which is in contact with a more rigid region than the one necessary for the massage. This drawback is due to the fact that the insert must have a sufficient rigidity in order not to completely give way under the body weight when walking, and often the rigidity necessary for walking is greater than the one necessary for comfort. Moreover, when compressing an elastic material, the resistance to compression and so rigidity increases with increasing compression. Therefore, the greater the compression is, the greater the hardness of the compressed material is.